The Boondock Saints

In Boston, Irish American fraternal twin brothers Connor and Murphy MacManus attend Mass, where the priest mentions the fate of Kitty Genovese, sparking an epiphany that inspires them to cleanse their hometown of evil. As they hunt down notorious gangsters with a brand of zealous vigilante justice, they become embroiled in a cat-and-mouse game with FBI Special Agent Paul Smecker, who's hot on their trail.